Electric forging and apparatus therefor



April 2, 1940. E. GASPAR ELECTRIC FQRGING AND APPARATUS THEREFOR FiledJune 30, 1939 3 Sheets-Sheet 1 4w X QQ hi; m w 1% WI P I I: III w 1 a Ih mmxmawfi R Q fimwfi RN w 3 April 2, 1940. E. GASPAR ELECTRIC FORGINGAND APPARATUS THEREFOR Filed June 30, 1939 3 Sheets-Sheet 2 Ap" 2, 1940.E. GASPAR ELECTRIC FORGING AND APPARATUS THEREFOR Filed June 30, 1939 3Sheets-$heet 5 g www ANN wmw @w 5. @w ENE Qmw Qww & $1 I fi v k I I I I1 1 Y 1% Q% Patented Apr. 2, 1940 EIECTRIC FOBGING AND APPARATUS EmericGaspar, London, England,

, London, England, a British Omes Limited company a-ignor to ApplicationJane 30, 1939, Serial No. 283,244 In Great Britain April :1, 1938 Thisapplication corresponds to the application of Gaspar and Omes Limited,Serial No. 12,637/1938 which was filed in Great Britain on April 27,1938.

This invention comprises improvements in or relating to electric forgingand apparatus therefor. It has previously been proposed to forge rods toa point by electrically heating while under tension so that as soon asthe material becomes softened it is drawn out until it breaks.

It has been found, however, that in some cases in tension forging thestructure of the steel may be damaged by overheating and burning, andalso that the points produced are not always identical in shape with oneanother. For

some purposes, such for example as the manufacture of projectiles, thepoints produced are too rounded and with some steels the points maybreak of! flat after reduction of the section has proceeded to a certaindegree. Again, steel should not be deformed unless it is hot enough,otherwise the structure of the metal will be damaged. With thepreviously existing apparatus however in which the tension was appliedat the same time as the initiation of the heating current, or otherwisecontrolled solely at the will of the operator, it was probable thatdeformation would be started before the proper forging temperature wasreached, 'It is an object of the present invention to improve theprocess in these According to the present invention a process ofelectric forging under tension is characterised by the fact that thetension is applied only after a the piece to be forged has reached apredetermined forging heat and that the heating current is cut oil, orat least reduced, prior to the application of the deformation undertension. It is found that in this way the forging operation can becaused to take place within the limits of forging temperature of thesteel under treatment and satisfactory tapered shapes can be produced,including particularly shapes corresponding to the pointed ends ofprojectiles. I

45 The application of tension to a workpiece may be initiatedautomatically by a heat-responsive element in the neighbourhood of or incontact with the heated portion of the workpiece. Again, the reductionor cutting-oft of the heating current 50 may be controlled, so as tooccur automatically, by a heat-sensitive device in the neighbourhood ofor in contact with the heated portion of the workpiece.

The invention further comprises an electric u forging apparatuscomprising in combination two work-holding vices for gripping theworkpiece at separated points along its length, means for supplyingelectric current to the workpiece through the work-holding vices to heatit, means for moving the vices apart so asto app y tension to the 5workpiece and a device for simultaneously cutting of! or reducing theheating current and initiating the operation of the means for moving thevices apart.

The heat-responsive element above referred 10 to may consist of anelectric eye" which is electrically connected to a relay, operation ofwhich cuts off or reduces the heating current and initiates the forgingmovement. The tension for forging may be applied by means of anhydraulic 15 ram operatively connected to one of the vices and under thecontrol of an hydraulic valve which is magnet-actuated, the magnet beingcontrolled by the heat-responsive element.

In some instances instead of, or in addition to 2 applying tension tothe workpieces the forging of the point can be effected by swaging toolswhich are applied at a time (corresponding to that of the application ofthe tension to the workpiece above described) after the workpiece 5 hasbeen brought to the desired heat and the forging operation is (asbefore) so conducted that the current is diminished or cut off beforethe reduction of the cross-section of the workpiece has proceeded toofar. 30

The following is a description by way of example of one form ofapparatus in accordance with the invention and of the process of theinvention as carried out therein.

In the accompanying drawings- 5 Figure 1 is a side elevation and Figure2 a plan of a forging machine;

Figure 3 is a diagrammatic representation of the working parts and ofthe electrical and hydraulic connections; 40

Figure 4 is a diagrammatic plan of an alternative construction,

Figure 5 shows the pointed structure produced, Figure 6 is a verticalsectional view taken substantially on the line 6-6 of Figure 4.

Referring to Figures 1 and 2.the forging machine comprises a bed plateil having longitudinal guideways I! supported on a framework i3 withinwhich are located, behind louvred cover plates H, the electricalstep-down transformer for supplying heating current and an electricallydriven pump for hydraulic powerfi These latter parts are not illustratedin detail as they are common practice in forging machines.

Upon the longitudinal guideways ii there are mounted two work-holdingvices I, I! which are capable of movement along the guideways. The viceI1 is insulated from the lathe bed and the two vices are connected tothe terminals of the step-down transformer above referred to so thatwhen a workpiece II is gripped so that it extends between the vices, theportion of the workpiece which spans the interval between them becomesheated to forging temperature.

Each of the vices comprises a body portion which supports a lower vicejaw I! and an hydraulic cylinder 28 containing a ram 2i which isconnected to an upper movable vice jaw 22.

The vice jaws is, I! are made removable from the portions of the vicewhich hold them and they are interchangeable with other vice jaws, thevarious vice jaws being shaped, where they meet together, so as to gripvarious desired shapes of workpieces. The jaw members ll, 22 are alignedwith one another in a direction parallel with the guideways of the bedplate so that the workpiece ll, when gripped, is parallel with theguideways. The vices I 4, ii are made of bronze or some other goodelectrical conductor. The vice i! is adjustably secured on the guidewaysby means of side rods 23 which are insulated from the vice and areconnected to a crosshead 24 operated by a screw 25. The screw 25 passesthrough a screwed nut 28 which is journalled in a transverse bracket 21at the end of the machine bed. The nut 26 carries at one end wormwheelteeth 28 which mesh with a worm 29 mounted on a shaft Ill. The shaft 30carries a sprocket 3! which is rotated by means of a chain 32 from ahandwheel N and thus the vice I! can be set, by rotation of thehandwheel, at any desired position along the bed.

The other vice i8 is connected by rods 34 to a crosshead 35 which ismade capable of sliding along the guideways i2 and is secured on the endof a ram 36 working in an hydraulic cylinder 31. The cylinder is boltedby flanges 34 to the bed plate ii. The hydraulic cylinder 31 is madedouble-acting so that it caniorce the vice iS'to move in eitherdirection. The vices i6, i1

are given suiiicient gripping force upon the workpiece to enable them toprevent the workpiece from sliding through the jaws under the tensionrequired for forging. Any other additional means for gripping the endsof the workpieces and preventing them from sliding through the vice jawsmay be provided if this is found desirable or necessary.

Between the vices and arranged in a position so that it points towardthe central portion of the workpiece i8 where it spans the interval fromvice to vice there is a photo-electric cell 40 which is sensitive to therise of temperature brought about in the workpiece by the heatingcurrent. Such a photo-electric cell is sometimes known as an electriceye." The cell 40 is so positioned and adjusted that upon the workpiecereaching the desired forging temperature it will actuate a relay 4|(Figure 3). The relay is energised by a supply circuit 42. Thecombination of electric eye and relay is well-known in itself andtherefore the construction of these parts is not indicated in detail inthe drawing. The relay 4!, when actuated, serves to break a circuit 43,44, 45 which normally supplies with current a magnet 48 of a clapperswitch 41. The switch 41 controls the circuit of the primary winding 48of the step-down transformer before referred to which is shown at 49 inFigure 3 and has a secondary winding 50. The circuit of the primarywinding 44 is energised from a power supply I. When the relay Itoperates to break the circuit 43, 44, 45 the clapper switch magnet 44 isdeenergised and the clapper switch opens, thus cutting oi! the supply ofpower to the transformer 4| and thereby cutting of! the heating currentfrom the workpiece II.

The relay 4! at the same time energises a control solenoid I! throughthe circuit ill, I44. The control solenoid I2 is connected by a rod llto a control lever II which projects from a valve box II. This lever andthe valve box can also be seen in the plan, Figure 2. The object of theenergisation of the solenoid i2 is to cause the ram 84 to be retractedand apply tension to the workpiece in order to draw it into a pointedshape between the vices I, ii. For this purpose the valve box II issupplied with oil under pressure from a pump is through a supply pipe81. It is not necessary to describe in detail the construction of thevalves but is suiiicient for the present purpose to explain that ondepression of the lever 84, either by hand or by the action of thesolenoid 82, the oil pressure is directed into the pipe II which leadsthrough a throttle valve 59 to the front end of the hydraulic cylinder31. At the same time the pipe 6!, which is in communication with theback end of the cylinder through a throttle valve I, is connected by theaction of the lever '4 in the valve box 55 with an exhaust pipe 62leading to an oil return sump 63 from which the pump 56 draws its supplyof oil. On the other hand, if the lever 54 is raised, the pipe 54 isconnected to the exhaust pipe 62 and the pipe I to the oil pressuresupply, thereby reversing the movement of the ram 36 and causing it toadvance. The lever 54 is urged upwardly by a spring 64 and the latch 65is capable of holding it down. The latch 65 is connected to a slidingrod 46 mounted at the side of the machine bed ll so as to extendparallel to the ram 36. The rod 68 is urged by a spring 61 in such adirection as to cause the latch to tend to slip over the lever 54 andhold it down as soon as it is depressed. Upon the rod 66 is a collar 64which can be set at any desired position and held by a screw. The colbar68 is in line witha striker 68 carried on the crosshead 35 and thus,when the ram 34 is caused to be retracted by depression of the lever 54,the movement will proceed until the striker 68 engages the collar 68 andwithdraws the latch 65. Thereupon (since the relay 4i will have beende-energised in the meantime by the fact that the workpiece has beensevered and that the electric eye" 40 is no longer focussed upon a fullyheated portion of the workpiece) the lever 54 will be forced upwardly bythe spring 64 and the movement of the ram will be reversed so as tobring it forward into position ready to operate upon a new workpiece.The throttle valves 59 and Bi serve to regulate the speed of movement ofthe ram, the one in the one direction and the other in the other andthus to determine the speed of the forging operation and the time takenfor the return movement, which latter should be sumcient to permit theoperator to prepare for the insertion of another workpiece.

The extent of the movements of the ram in both directions is limited bystops. The adjustable rod 10 which is able to slide in a boss Ii on thetop of the cylinder 31 constitutes a back stop to prevent undueretraction of the vice l6 and the two screwed rods I2 which pass throughthe the crosshead 'II are provided with heads I! to constitute a frontstop. The heads ll carry sprockets II which are connected by chains IIand one of the spockets has a handle II. By this means the two screws 12can be simultaneously rotated to an equal extent and brought into anydesired position of adjustment.

The vices I8, H are controlled from the valve box I! by a lever 11parallel to the lever l. The lever 'II operates the valves in the valvebox I! which serve to admit fluid under pressure to the pipe ll leadingto the upper endof the cylinders 2| when the lever is depressed, whileat the same time connecting the pipe IO, connected to the lower ends ofthe cylinders, to the exhaust pipe 62. Depression of the lever II willtherefore close the vices I6. II simultaneously upon the workpiece. Onthe other hand, when the lever ;is raised into the position indicated inFigure 3 the connections of the pipes and I! to pressure and exhaustrespectively will be reversed and the vices will be opened to releasethe workpiece, or rather the portions of it which remain in the vicesafter the forging operation.

The pressure which is applied for holding the workpiece and for theforging operation can be regulated by means of a by-pass relief valve .0

on the delivery side of the pump 56. The relief valve has a screwed stemll screwing down of which modifies the pressure of the relief valvespring and thus determines the hydraulic pressure at which the systemoperates.

On a branch 82 from the pipe 18 there is connected a switch controlcylinder 83. This contains a piston and a return spring 84 and serves tooperate a piston rod 85 in such a way that the presence of hydraulicpressure will cause the rod II to be pressed forward out of the cylinderinto the position shown in the drawings. The rod 85 is connected to twoswitch arms 88, 81 of a double-pole switch in the supply circuit to thetransformer winding 48. Failure of the hydraulic pressure will thereforelead immediately-to the current being cut of! but as long as thepressure is maintained in the pipe I8 and the vices are thereforeclosed, the transformer will be energized, subject of course to thecontrol of the clapper switch 41 already described.

In addition to the controls already described there is a push button 90which normally closes the circuit leading from the relay through thewires 43, 44, but which, when pushed, breaks this circuit and makesanother through the wires 9|, 92 which by-passes the relay II andenergizes the solenoid 52 as an alternative to the energisation of thissolenoid by the relay. Consequently the operator, if he desires, can cutout of operation the "electric eye" 40 and cause the transformer '48 tobe tie-energised by operating the push button 90, at the same timeapplying the tension forging force to the workpiece through the actionof the solenoid 52. In this case the control of the operations iseffected by hand instead of automatically by the electric eye."

In the operation of the apparatus therefore the operator begins with thelevers 54, II in their uppermost position as indicated in Figure 3. Thevice jaws I9, 22 of both vices will then be open and the ram 36 will beadvanced to its full extent. After placing a workpiece I8 in position,the operator depresses the lever I'I, thus closing the vices andactuating the hydraulic switch 81 to close the transformer circuit. Assoon as the work reaches forging temperature the electric eye lloperates the relay ll and breaks the transformer circuit byde-energising the clapper switch magnet it. At the same time the relayMenergises the solenoid l2 and draws a down the lever ll, therebysetting the ram in movement to draw the vice I6 away from the vice a I1and cause the work to be drawn out. with the normal setting of theparts, this movement will continue until the workpiece is drawn out to 7two pointed pieces somewhat similar to the lilustration in Figure 5,although the degree of 10 taper of the point depends not only upon thetemperature of the workpiece but also upon the distance apart of thevices before the'operation is commenced and the speed of the'drawing-operation, which latter can be regulated by means of thethrottle valves '59, ii. If it is desired merely to forge a thinnerplace in the workpiece, and not completely to sever it, the stop III isadjusted to terminate the motion before the workpiece has been fullysevered.- Immedigo ately before the'end of the movement of retraction ofthe ram 36 the striker 69 is made to engage the collar 60 and, withdrawthe latch 65, thereby permitting the lever 54 to rise and causeing theram I8 to stop and to begin a forward movement. The operator raises thelever ll, thus opening the vices I6, I1 and removes the workpiece. Ifthe throttle valve 6| is suitably adjusted he will have time to insertanother workpiece before the ram 36 completes its forgo ward movement,upon the termination of which he will lower the lever 11 again andthereby close the vices upon the workpiece. Thereafter therecommencement of the drawing operation depends upon the workpieceacquiring the appro- 86 priate temperature which is observed by the"electric eye I, or altemativelyby the operator. A

It should be observed that if desired the screw 25, which serves toadiust the vice Il, may be made hollow so that a long length of bar canbe fed into the vice jaws through the screw, and in that case a seriesof workpieces could be severed one after another by feeding in a freshpiece of bar between the vices after each severing'opa workpiece III maybe held and heated as already described. In addition to the clampingjaws the vices have supporting ball bearings I20 which surround theworkpiece and are able to support it for rotation even after the vicejaws 9 have been released. Between the vices H8, 5

I I! there are mounted two cradles I2I, I22 which are pivoted below theworkpiece and extend upwardly one at the front and one at the rear asillustrated in Figure 4 and carry at their upper ends on each side ofthe workpiece rotatable swaging rollers I23. The swaging rollers aremounted on spindles the axes of which are parallel to the axis of theworkpiece Ill and the spindles I24 carry at their ends sprockets I25.The sprockets are driven bychains I28 from a larger sprocket coaxialwith the pivot of the cradles I2I, I22. The cradles are capable of beingrocked so as to advance the swaging rollers I23 into contact with theworkpiece II! by means of a rightand left-hand screw I21 which 1' piecesimilar to the electric eye" ll ofl'igures 1 to 3. In the operation oithe device the workpiece is first heated by applying the current afterthe vices H6, ill have been closed together upon the workpiece. As soonas the work becomes hot enough for forging, the electric eye" operates arelay similar to the relay 4i and the vices are so connected that thevice Jaws II! are released from the workpiece, thus freeing itforrotation. At the same time the rollers I23 are set in motion and theoperator, as soon as he sees these events happen, actuates thehand-wheel I28 to close the swaging rollers I23 upon the workpiece. Theswaging rollers, since they are being rotated and the workpiece isrotatably mounted in the bearings iZG, will cause the workpiece torotate while they are being forced inwardly into it and as a result theworkpiece is swaged to a shape similar to that shown in Figure 5 and thetwo halves are separated from one another. Thereafter the swagingrollers are withdrawn and the workpiece is taken out of the electrodesH6, H1. It will be understood that with this arrangement the vice jawsdo not move along the bed on which they are mounted and, except for somemeans of longitudinal adjustment, no necessity exists for suchlongitudinal movement. The cylinder 3! and ram 36 would therefore beomitted from such a construction.

While a particular shape of swaging roller has been illustrated which isadapted to produce points like the end of a projectile, it will beunderstood that any other shape of swaging roller could be'adopted ifdesired. The action of the rollers can be assisted if desired, byapplying tension, providing the vice I I6 is made longitudinallymovable. Tension applying means similar to that hereinbefore describedmay be employed for this purpose.

I claim:

1. An electric forging apparatus comprising in combination twowork-holding vices for gripping a workpiece at separated points alongits length, means for supplying electric current to the worktheworkpiece through said gripping means to heat the workpiece, means forapplying force to the workpiece to deform and reduce the sectionthereof, and means responsive to a predetermined increase in temperatureof said workpiece for simultaneously reducing the supply of electriccurrent thereto and initiating operation oi said force applying meansthereon.

3. Electric forging apparatus comprising in combination two work-holdingvices for gripping a workpiece at separated points along its length,means for supplying electric current through the work-holding vices tothe workpiece to heat the latter, means for rotating the workpiece aboutits own axis, swaging rollers mounted so as to be applied to theworkpiece to reduce the section thereof, and means responsive to apredetermined increase in temperature of the workpiece for reducing theheating current, for applying the swaging rollers to the workpiece, andfor initiating operation of said workpiece rotating means.

4. In an electric forging apparatus, the combination with means operableto grip a workpiece, of means for supplying electric current to theworkpiece through said gripping means to heat the workpiece, means forapplying force to the workpiece to deform and reduce the sectionthereof, electrical means for simultaneously initiating operation ofsaid force applying means and reducing said heating current, meansincluding a thermal device responsive to rise in temperature of saidworkpiece for energizing said electrical means, and manually controlledmeans for energizing said electrical means independently of theoperation of said thermal device.

ELAERIC GASPAR.

